Saturday, 3 January 2015

Some Blind People Use Echolocation to 'See'

Soundwaves help to judge position of objects in surrounding area, study shows

WebMD News from HealthDay

By Mary Elizabeth Dallas

HealthDay Reporter

THURSDAY, Jan. 1, 2015 (HealthDay News) -- Some people who are blind develop an alternate sense -- called echolocation -- to help them "see," a new study indicates.

In addition to relying on their other senses, people who are blind may also use echoes to detect the position of surrounding objects, the international researchers reported in Psychological Science.

"Some blind people use echolocation to assess their environment and find their way around," study author Gavin Buckingham, a psychological scientist at Heriot-Watt University in Scotland, said in a journal news release.

"They will either snap their fingers or click their tongue to bounce sound waves off objects, a skill often associated with bats, which use echolocation when flying. However, we don't yet understand how much echolocation in humans has in common with how a sighted individual would use their vision," Buckingham said.

To investigate the use of echolocation among blind people, the researchers divided participants into three groups: blind echolocators, blind people who didn't use echolocation, and control subjects that had no problems with their vision.

All of the groups were told to estimate the weight of three cubes that were the same weight, but different sizes.

The study showed that people who use echolocation misjudged the weight of the cubes. Meanwhile, the blind people who did not use echolocation were able to correctly assess the weight of the boxes because they had no idea how big each one was, the researchers explained.

"The sighted group, where each member was able to see how big each box was, overwhelmingly succumbed to the 'size-weight illusion' and experienced the smaller box as feeling a lot heavier than the largest one," Buckingham said.

"We were interested to discover that echolocators, who only experienced the size of the box through echolocation, also experienced this illusion," Buckingham said. "This showed that echolocation was able to influence their sense of how heavy something felt. This resembles how visual assessment influenced how heavy the boxes felt in the sighted group."

The researchers noted that these findings are consistent with other research that suggests that blind people who use echolocation rely on the visual areas of the brain to process echolocation information.